Photocatalyzed relay cleavage for the upcycling of gem-dimethyl-type plastics

Activation and cleavage of chemical bonds are pivotal for the chemical recovery of plastics back to value-added products. The gem-dimethyl motif in plastics enhances physicochemical properties via steric reinforcement of quaternary carbon centers, yet its inherent chemical inertness concurrently impedes the degradative process. We demonstrate a photocatalytic relay bond cleavage protocol for gem-dimethyl-type plastic degradation, in which chlorine radical from photoexcited ferric trichloride enables the activation of inert C(sp³)-H bonds in gem-dimethyl motifs followed by two successive C-C bond cleavages via divergent mechanistic pathways. Mechanistic investigations reveal that the first C(sp³)-C(sp³) bond undergoes homolytic cleavage via radical-type β-scission, and then the second C(sp³)-C(sp²) bond undergoes heterolytic cleavage via ionic-type O-O bond dissociation inducing a 1,2-aryl migration. This efficient protocol achieves effective degradation for gem-dimethyl-type plastics, offering an economically sustainable strategy for plastic waste valorization.